1. Field of the Invention
The present invention relates generally to medical ventilation tubes and, more particularly, to myringotomy ventilation tubes that can be placed in the tympanic membrane of the ear to drain fluid and alleviate a buildup or reduction of pressure in the middle ear.
2. Description of Prior Art
The installation of tubes in the tympanic membrane, which separates the middle ear from the outer ear, is a well-known remedy for treating inflammation of the middle ear or otitis media. Typically, a myringotomy is performed to create an opening in the tympanic membrane and a vent or drain in the form of a tube is inserted into the opening to permit drainage of fluid from the middle ear to alleviate a buildup, or reduction of pressure in the middle ear cavity. The tube functions to maintain the opening in the tympanic membrane for a sufficient period of time following the surgery to allow pressure to equalize between the middle and outer ears. Frequently, the condition of buildup or reduction of pressure in the middle ear cavity which the tube is intended to alleviate requires that the tube remain in place for a significant period of time ranging in duration from about six to about twenty four months.
A variety of ventilation tubes for insertion into an opening in the tympanic membrane have been introduced over the years. Prior art ventilation tubes without flanges at either end are easy to insert into the myringotomy opening but are disadvantageous in that they can be accidentally extracted from the tympanic membrane. On the other hand, ventilation tubes having flanges at one or both ends are less likely to be accidentally extracted from the tympanic membrane but are difficult to insert into and extract from the myringotomy openings, tending to enlarge the myringotomy openings such that the tendency of the tubes to fall out of the membrane increases. Attempts to fabricate prior art ventilation tubes of softer materials help alleviate problems associated with insertion and removal of the tubes through openings in the tympanic membrane but contribute to problems related to bending or buckling of the tubes during insertion while detracting from the ability of the tube to maintain an opening in the tympanic membrane.